Ladder jack



C. E. KRAMER May 2, 1933.

LADDER JACK Filed Aug. 17, 1931 Arroemgfs.

Patented May 2, 1933 UNITED STATES teams Parent CARL n. KRAMER, ofFAInvIEw VILLAGE, on o, Assienoa TO TH cLnvnn-aiin waouenr rnonucrscomrenxor cLnvnLei-inon o, A oonroe-Arron or onro;

LADDER JACK This invention relates to ladder jacks and is an improvementover my prior Patent No. 1,578,529 granted March 30, 1926.

The most important feature of the present invention resides in provisionof a safety means whereby the probability of accident due to breakage,to persons using the ladder jack embodying the invention, is practicallyeliminated.

Another object of the present invention is to provide a ladder jackwhich is simple in construction, efiicient and inexpensive tomanufacture.

Reference should be had to the accompanying drawing forming a part ofthis specification in which Figure 1 is a perspective View of a ladderand a ack mounted thereon;

Fig. 2 is a top plan view of the jack with portions omitted;

Fig. 3 is a top plan view of the upper part of the jack. 7

Fig. 4 is a fragmentary side elevational view on an enlarged scaleshowing the con struction embodying the present invention;

Fig. 5 is a top plan view of that shown in Fig. 4.

Referring to the drawing, 1 and 2 indicate side members which at theirforward ends are pivoted as indicated at 3 upon a post 4. This post mayconveniently be made as a sheet metal member which is folded upon itselfto form a T-base 4 and has upwardly projecting ears which at their upperends are spaced apart as indicated at 4* to receive between them apivoted bar 5. The ends of the side members 1 and 2 are pivoted on theside flanges of the base 1 At the opposite ends of the side members 1and 2 there are secured U-shaped yokes '6 and 7 which are adapted topass around the opposite side rails of a ladder. In order that the yokes6 and 7 may properly engage with the side rails of the ladder, themembers 1 and 2 are bent at a slight angle as indicated at 1 and 2 andto this bent portion one side of each U-shaped yoke is attached.

In order to prevent the side members 1 and 2 from moving away from theladder whe o ce m u ed ther en; at l ast one of the-side members isprovided with a downwardly extending hook 8 which will extend behind oneof the rungs of the ladder and thus positionand retain the. side membersagainst moving away from'the ladder. 1 f The bar 5 extends. through aslot which is formed in a member 9,.which member has pivotally securedto it, two diverging members 10 and .11. These members 10 and 11 attheir outer ends are provided with hook shaped portions which areadapted to extend around the side rails .of aladder and to'rest upon oneof the; rungs of the ladder- The bar 5 is provided witha plurality ofnotches 5? and the member 9 engages in these notches and, so holds orsupports the pivoted ends of theside members land 2.

These ladder jacks are in practice used; in p pairs, each jaclr being:mounted upon one" of a pair of ladders which are spaced apart, Betweenthe jacks there extends a platform or, plank. The side members 1. andf2adapted to receive and support oneendot' such a platform or plank;

When the jack is used as above described the load on the platform orplan'k and the bending moments incident thereto are trans; mitted inlargepart directly'to the side ralls oft-he ladder, which portions .ofthe ladder; arethe strongest portions and (will withstandgreaterstresses and strains than the rung of the ladder couldpossiblystand.

The adjustability of the strap; spect to the member. 9 permits thej ackto be. adjusted with respectto; the ladder so as to? have the sidemembers l and 2 in a substan-: tially horizontal plane and thus provide,for difierent angular positions of the ladder with respect-to therwallor smaller. object against which-the upper end ofthe ladder is placed.

5 with re Due to the pivoted construction the jac may becompletelyfolded so that when not in use it will occupy but. a]limitedamount of.

space. V

7 It will be apparent that there can be sub,

' stantially' no side' sway to the jack because efiect a triangle and astifi resisting structure.

Additionally the U-shaped members 6 and 7 engage with the side railsvery snugly and therefore turning of the members 6 and 7 on the siderails of the ladder is prevented. I

In Figs. 4 and 5 there is illustrated the safety means embodying thepresent invention.

The pivoted end of the bar 5 is provided with an arcuate slot 13 in itsunderside within which is normally disposed the shank or body of a pinor rivet 12 which has its opposite ends rigidly secured to theprojecting ears of the post 4. i It will, therefore, be readily seenthat should the pivot at the end of the bar'5 become broken or otherwiseaccidentally disengaged, the end of the bar 5 and the post 4 will notbecome separated due to engage ment' between the pin 12 and the slottedportion of the bar 5, the load being taken by the .pin 12. Thisconstruction, therefore, provides a ladder jack which is practicallysafe, even though portions of the jack should become broken oraccidentally disengaged.

While I have described the preferred embodiment of the invention, it isto be understood that I am not to be limited thereto inasmuch as changesand modifications may be resorted towithout departing from the spirit ofthe invention as defined by the appended claims. y

Having thus described my invention I claim: r i

1. A ladder jack comprising a pair of side members flexibly connected atone end so as to be relatively movable at the other, rail engagingmembers associated with the free ends of said side members, a barpivotally connected adjacent the connected ends of said side members,rail hook members adjust-ably connected with the free endof said bar,and interengaging means between the end of said bar and said sidemembers and adapted to support'the side member independently of the barpivot in casev of accidental dis-engagement.

2. A ladder jack comprising a pair of side members flexibly connected atone end so as to be relativelymova'ble at the other, railengagingmembers associated with the free ends of said side members, abar pivotally connected adjacent the connected ends of said sidemembers, ,rail hook members adjustably connected with the free end ofsaid bar,'and a pin and slot connection between the end of said bar andsaid side members and adapted signature. I

i CARL E. KRAMER.

to support the side member independently of- L the bar pivot in case ofaccidental disengagement. 7 I a '3. A ladder 1ack comprising a pair ofside members, a'bracket to which said side mem-j bers are connected andhaving'a pair of spaced ears,er a1l engaging members asso: ciatedwiththe free ends of said side meme

